1. Field of the Invention
The present invention relates to a stylus pen to be used mainly for a tablet or the like. More particularly, the present invention is concerned with a stylus pen to be used for an electrostatic coupling type tablet and suitable for performing coordinate input and menu selection.
2. Prior Art
A prior art stylus pen of this type will be described below with reference to FIGS. 26 through 28.
FIGS. 26 and 27 illustrate a conventional stylus pen, which stylus pen, indicated at 11, generally comprises a first case 12, circuit portion 13, cap 16, holder member 18, spring 19 and second case 20.
As shown in FIGS. 26 and 27, the first case 12, which is an elongated case formed of an insulating material such as ABS resin for example, has a peripheral portion 12a and a semicircular side wall 12b provided at one end of the peripheral portion 12a. The peripheral portion 12a, having semi-arcuate inner and outer peripheral surfaces, is formed so as to become smaller in diameter from one end side thereof where the side wall 12b is positioned toward the opposite side, namely the other end side. In the other end of the peripheral portion 12a is formed a receptacle part 12c for a cap 16 which will be described later, while on the inner peripheral surface of the peripheral portion 12a is formed a receiving part 12d for a substrate 14 which will be described later. Further, a cutout 12e for fitting therein one end of a later-described spring 19 is formed in the side wall 12b .
The circuit portion 13 comprises a substrate 14 formed of such material as paper or a phenolic resin, a push-button switch 15 provided with an operating part 15a and a terminal part 15b, and a detector 17 constituted by a conductor piece for detecting the position of the stylus pen 11 on a tablet 22. The switch 15 is turned on and off by pushing the operating part 15a, and its terminal part 15b is soldered to one side of the rear end of the substrate 14, namely the right end upper surface of the substrate in FIG. 27. On the other hand, to the front end of the substrate 14, namely the left end of the substrate in FIG. 27, is mounted the detector 17 also by soldering and is covered with a cap 16 formed of a synthetic resin material. On the upper surface of the substrate 14, though not shown, is formed an electronic circuit for processing a signal detected by the detector 17. The electronic circuit is connected electrically to both terminal part 15b of the switch 15 and detector 17, and there is provided a cable (not shown) which is connected to the said electronic circuit.
The cap 16 is put on the receptacle part 12c of the first case 12 and longitudinal edges of the substrate 14 are put on the receiving part 12d of the first case 12, whereby the circuit portion 13 is accommodated within the first case. Though not shown, the cable connected to the electronic circuit on the substrate is drawn out of the first case 12 through a through hole formed in the peripheral portion 12a of the first case.
A cylindrical holder member 18 formed of a synthetic resin material such as polyacetal has a cylindrical peripheral portion 18a and an end face portion 18b . The open side of the peripheral portion 18a is formed with a pair of cutouts 18c extending through the peripheral portion toward the inner part to thereby form a flexible part 18d as shown in FIGS. 26 and 27. The inside and outside walls of the flexible part 18d are provided with protuberances 18e and 18f, respectively. Further, in the inner wall of the peripheral portion 18a are formed a pair of slots 18g which are opposed to each other with 180.degree. phase shift.
Both longitudinal edges at the rear end of the substrate 14 are fitted in the paired inner slots 18d to receive and hold the substrate rear end. In this state, the protuberance 18e of the flexible part 18d is in abutment with the operating part 15a of the switch 15.
The holder member 18 is accommodated slidably within the first case 12 in an abutted state of part of its peripheral portion 18a with the inner peripheral surface of the first case.
As shown in FIG. 27, one end of the spring 19, which is formed of a metallic material, is fitted in the cutout 12e formed in the side wall 12b and is thereby mounted within the first case 12, while the opposite end thereof is brought into abutment with the end face portion 18b of the holder member 18 and is thereby accommodated within the case 12.
The second case 20, which is an elongated case formed of an insulating material such as ABS resin for example, is provided with a peripheral portion 20a having arcuate inner and outer peripheral surfaces and is also provided with a semicircular side wall 20b formed at one end of the peripheral portion 20a, as shown in FIGS. 26 and 27. As is the case with the first case 12, the peripheral portion 20a is formed so as become smaller in diameter gradually from its one end side where the side 20b is positioned toward the opposite side, namely the other end side. In the other end of the peripheral portion 20a is formed a receptacle part 20c for the cap 16. On the inner peripheral surface of the peripheral portion 20a are provided a protuberance 20d and a receiving part 20e for the substrate 14. Further, in the side wall 20b is formed a cutout 20f for fitting therein of one end of the spring 19.
As shown in FIG. 27, the second case 20 is mounted to the first case 12 with an adhesive or the like. When the first and second cases 12, 20 are thus combined together, the holder member 18 and the spring 19 are accommodated within both cases, one end of the spring 19 which has been fitted in the cutout 12e of the first case 12 is also fitted in the cutout 20f, the receptacle part 20c is in abutment with the peripheral surface of the cap 16 and holds the cap 16 slidably in cooperation with the receptacle part 12c of the first case, and the receiving part 20e is in abutment with the longitudinal edges of the substrate 14 and holds the substrate also slidably in cooperation with the receiving part 12d of the first case. Further, the detector 17 is positioned near the center between the inner walls of the first and second cases 12, 20 to detect the position of the stylus pen 11 on the tablet 22.
How to assemble the stylus pen 11 will now be described. First, the terminal part 15b of the switch 15 and electronic components (not shown) are mounted by soldering onto the substrate 14. Next, the detector 17 is mounted by soldering to the front end of the substrate 14, then the cap 16 is mounted and then, though not shown, a cable is connected to the electronic circuit of the substrate 14 to assemble the circuit portion 13. Next, the rear end of the substrate 14 is fitted in the paired slots 18g of the holder member 18 and is thereby accommodated within the holder member to render the substrate and the holder member 18 integral with each other. Then, one end of the spring 19 is fitted and mounted in the cutout 12e formed in the side wall 12b of the first case 12, and the cable connected to the electronic circuit of the substrate 14 is drawn out of the first case 12 through a through hole formed in the peripheral portion 12a of the first case. Thereafter, the cap 16 is put on the receptacle part 12c of the first case 12 and the longitudinal edges of the substrate 14 are put on the receiving part 12c of the first case to accommodate the circuit portion 13 within the first case 12.
Subsequently, the one end of the spring 19 which has been fitted in the cutout 12e of the first case 12 is also fitted in the cutout 20f formed in the second case 20. Further, the receptacle part 20c of the second case is brought into abutment with the peripheral surface of the cap 16 and the receiving part 20e of the second case is abutted with the longitudinal edges of the substrate 14, thus allowing the second case 20 to be put on the first case 12. In this state both are bonded together.
In this way the assembly of the stylus pen 11 is completed. After the assembly, the opposite end of the spring 19 is in abutment with the end face portion 18b of the holder member 18.
The operation of the stylus pen 11 will now be described. In the stylus pen 11, as shown in FIG. 28, the cable drawn out from the through hole formed in the peripheral portion 12a of the first case 12 is connected to the tablet 22 of the electrostatic coupling type, which tablet is connected to a body 23 of a computer, an electronic game machine, or the like. In the portion near the surface of the tablet 22 are buried a plurality of signal lines in the form of a lattice and at predetermined intervals in both X and Y axis directions. A control means (not shown) which is provided within the tablet 22 makes control so as to pass an alternating current successively in a switched manner for each of the said signal lines. The signal lines are each coupled electrostatically with the detector 17, and a maximum detection output is obtained from the detector 17 when an alternating current is passed through the signal line closest to the detector 17. Thus, the control means detects the position of the stylus pen 11 on the tablet 22 by determining to which signal line an alternating current was flowed when the detector 17 produced the maximum output. This detection of the position is performed time-division wise in an alternate manner in X and Y axis directions. An input operation using the tablet 22 is performed by gripping the stylus pen 11 and pressing the cap 16 to a desired position on the tablet. As a result, the cap 16 is pushed into the first and second cases 12, 20, and the substrate 14 engaged with the cap 16, as well as the holder member 18 fitted on the substrate 14, slide within the first and second cases while compressing the spring 19, so that the protuberance 18f formed on the flexible part 18d of the holder member 18 come into abutment with the protuberance 20d of the second case 20. Upon further pressing of the cap 16 in this state, the protuberance 18f is pushed in by the protuberance 20d, resulting in that the flexible part 18d bends inwards by virtue of its elasticity and the protuberance 18e of the flexible part 18d pushes the operating part 15a of the switch 15, whereby the switch 15 is kept on and this information is transmitted to the tablet 22. As the stylus pen 11 is moved on the tablet 22 in this state, the position of the stylus pen on the tablet is detected on the basis of an output signal provided from the detector 17 in accordance with the foregoing principle, and signals responsive to movements of the stylus pen 11 are provided from the tablet 22 to the body 23, whereby the cursor on a display (not shown) of the body 23 moves to draw, for example, graphics on the display.
The inputting operation for graphics or the like can be stopped by moving the cap 16 away from the upper surface of the tablet 22, whereupon the holder member 18 slides under the restoring force of the compressed spring 19, the protuberance 18f of the flexible part 18d goes away from the protuberance 20d of the second case 20, the flexible part 18d reverts to its original state, and the operating part 15a of the switch 15 is no longer pushed by the protuberance 18e of the flexible part 18d , so that the switch 15 turns off and the resulting signal is transmitted to the body 23 through the tablet 22.
According to the conventional stylus pen structure described above, upon release of the cap 16 from the upper surface of the tablet 22, the holder member 18 slides under the restoring force of the compressed spring 19 and the protuberance 18f of the flexible part 18d leaves the protuberance 20d of the second case 20. However, there has been a fear of occurrence of the following inconvenience. As a result of repetition of such inputting operation, both protuberances 18f and 20d rub each other to roughen the sliding surface, the frictional force between the protuberances 18f and 20d becomes larger than the restoring force of the spring 19, the holder member 18 becomes immovable with the protuberance 18f pushed in by the protuberance 20d, and hence the switch 15 cannot be turned off.
Besides, the switch 15 is mounted on one side of the substrate 14 and it is necessary to use the holder member 18 provided with a cam mechanism for converting the moving direction of the substrate 14 into an operational direction of the operating part 15a of the switch 15 to press the operating part 15a. Therefore, it is required to ensure within the stylus pen 11 a space for all of the size of switch 15, the thickness of the substrate 14 and both protuberances 18f, 20d, with the result that the diameter of the stylus pen 11 increases and the stylus pen is compelled to become larger in size.
Moreover, since the first case 12 and the holder member 18 are in face contact with each other, a high frictional force is created at the time of sliding motion of the holding member 18 and there arise large variations in such force. Therefore, the operator is required to operate the stylus pen 11 with a force greater than the said frictional force, resulting in that the force required to operate the switch 15 and applied to the pen point, namely the cap 16, also fluctuates and thus it is difficult to keep constant the quality required for the stylus pen.
Further, the detection performance of the detector 17 depends on the state of mounting of the detector and in this connection the soldering work for mounting the detector to the substrate 14 is a minute manual operation and is troublesome. Thus, an increase of product cost results.